Westonbirt School is a co-educational independent day and boarding school for boys and girls aged 11 to 18 located near Tetbury in Gloucestershire in South West England. Founded in 1928. The historical Westonbirt House is part of the school. Westonbirt Prep School is located within the 210 acre grounds of Westonbirt School.

Westonbirt School was founded by the Martyrs' Memorial and Church of England Trust (now known as the Allied Schools), which had acquired Westonbirt House and converted it into a school. During World War II, the premises were used by the Air Ministry and pupils and staff were evacuated to Wiltshire due to the Blitz. Six former pupils died during the war and a memorial scholarship was set up in their memory; children of British military personnel are entitled to discounts.

In 2002, Westonbirt acquired Querns School to become its preparatory department. Seven years later it absorbed Rose Hill School to form the prep school Rose Hill Westonbirt. In September 2013 Rose Hill Westonbirt School was renamed Westonbirt Prep School. Wishford Education, a provider of independent education in the UK, acquired Westonbirt School in 2018.

As of September 2019, Westonbirt became co-educational and accepted boys into year 7, and in years 8,9 and 12 from September 2020.

Pupils are approximately one-third boarders and two-thirds day girls and boys. All boarders are members of one of the following houses:

Dorchester, named after Dorchester House iin London, owned by Robert Stayner Holford, also owner of Westonbirt House, which served as the American Embassy from 1905 and 1912 and was demolished in 1929 to be replaced by the Dorchester luxury hotel. Dorchester dormitories are located in the old servants' quarters at the top of the house, including the school's central tower, currently part of the Dorchester House Mistress' rooms.

Badminton, named after Badminton House with dormitories located in the west wing of the house on the second floor.

Beaufort, named after Beaufort Polo Club.

Gloucester, which houses Year 12 girls. Dormitories are located around the courtyard, on the first floor.

Holford, named after Robert Holford. This boarding house is exclusively for Year 13 students and is located several miles away in Tetbury. The building was formerly Ilsom House, a residential care home and was acquired in 2022.

A new Junior boarding house, Sedgwick, is in development onsite for pupils from Years 6-8. This will be open in early 2024.

The majority of the classrooms at the school are located in the courtyard, an area that was stables during the buildings' life as a stately home. Half of the sixth form dormitories are built above these classrooms. The new sixth form block was completed in 2008 and is located between the Science Block (opened in 1993 which contains the Art Department, D.T workshops, Science laboratories and the main I.T suite) and the courtyard classrooms.

In September 2012 the Marriott Music Centre was opened. Named after former chairman of governors this was designed by Bath-based architects DKA and built by Steele Davis between April and August 2012. It contains three learning spaces: The Technology Room, named The Friends’ Room in appreciation of a substantial donation by The Friends of Westonbirt. The Greenwood Scott Studio and the Ensemble Room, known as the Harborne Room, again in recognition of a substantial donation. This new centre complements the Camelia Building, a small practice area for music pupils, originally a greenhouse. The main school building is centred on the reception and the great hall, which has a marble fireplace and large organ overlooked by a balcony. In 2005 a new sports hall was opened by the Prince of Wales and Duchess of Cornwall. It features 25m swimming pool, courts and a gym, which is open to members of the public.

The grounds include a lake, amphitheatre, grotto, fountains and a set of Italianate gardens. Many of the fields around the school are rented out to farmers for cattle grazing or are used to keep horses either belonging to the local stables or to the pupils themselves. The school now owns the church, St. Catherine's, which is located within the grounds and which was originally the local parish church; Westonbirt pupils attend the church regularly.

The school library, made up of a separate ante-library and larger non-fiction library, was recently renovated using funding from an anonymous donor.

The school has a large conservatory known as the Orangery which includes a stage and balcony used for school ceremonies and drama productions. A basement contains the costume wardrobe where dramatic costumes and props are kept, originally the house's bomb shelter during World War II.

In 2022-23, eight new Walled Garden Classrooms were opened; these were designed and built to be in keeping with greenhouses which were formerly located there. A new Sports Zone also opened, which includes an Astroturf, cricket pitches and tennis and netball courts.

Work on a new Prep School building is scheduled to commence in autumn 2023.

• Westonbirt Arboretum

• Maxine Audley, actress
• Georgia Byng, children's author
• Pamela Carruthers (1916–2009), showjumping course designer
• Betty Clay (née Baden-Powell), scout and guides leader
• Lady Emily Compton, fashion model, stylist, and magazine editor
• Sheila Denning, painter.
• Angela Flowers, art gallerist.
• Baroness Garden, politician & Deputy Speaker of the House of Lords
• Anne Grosvenor, Duchess of Westminster (née Sullivan), race-horse owner, in particular the steeplechaser Arkle.
• Anna Hornby, artist
• June Jacobs, peace activist and campaigner for Soviet Jews.
• Diana Lamplugh, Charity founder and campaigner (1936-2011)
• Patricia Llewellyn, television producer, businesswoman
• Aileen McCorkell, the founder and first president of the British Red Cross branch in Derry.
• Mercia MacDermott, historian, writer
• Natasha Rufus Isaacs, socialite, co-founder of Beulah London
• Honor Salmon (née Pitman) (1912-1943), Air Transport Auxiliary Pilot
• (Susan) Pamela Rose (née Gibson), Bletchley Park translator, actress, teacher & NSPCC vice-president. Sister of Lord Gibson, married to Jim Rose.
• Julia Quinn, romance author of Bridgerton series
• Jane Sinclair, priest.
• Salma Sobhan, Bangladeshi barrister, human rights activist
• Patsy Toh, Chinese pianist
• Ruth Watson, hotelier, food critic, broadcaster

• Official website
• Profile on the ISC website
• Westonbirt School Foundation

51°36′21″N 2°11′44″W / 51.60583°N 2.19556°W / 51.60583; -2.19556